Fuel injectors are used, for example, in fuel injection systems in motor vehicles. To be able to test these during manufacture thereof or also subsequently in a repair shop, specially adapted test devices are used that are specifically adapted to each particular fuel injector type. For many special types of fuel injectors, for example, piezo fuel injectors of the subtype “active low,” thus piezo fuel injectors, where an injection valve is closed in the presence of an operating voltage (fuel injection into a cylinder is interrupted), testing is only possible, if at all, during manufacturing and only of individual components of the corresponding fuel injector. Known methods provide for testing of a fuel injector following the manufacture thereof.
The German Patent Application DE 10 2007 038 537 A1 discusses a test device and a method for testing an actuator of a fuel injector, the fuel injector being a piezo fuel injector. A test voltage is applied in steps or steplessly to the fuel injector, and a detected variation in a characteristic of an electrical quantity of a total resistance of the fuel injector ensuing during the change in the test voltage is measured.